[Buildroot] need help making bootable image

[Buildroot] need help making bootable image

[Jacob Sullivan]

Current status.  I have a buildroot ISO image that I can boot in qemu and a buildroot ext2 image that I can mount either in ubuntu or in qemu when I boot with the ISO image.  The changes that I made to the default build are minimal.  I added ext2 to buildroot and the kernel, added nano to buildroot and fdsk to busybox.  I also changed the tty in buildroot to tty1 so that I could get a console prompt when I booted in qemu.  I made an empty disk image, mounted it and made a primary partition formatted ext2, mounted that and copied in the root file structure.  I then unmounted it and tried to install grub on the image.  ubuntu has grub 2, and I couldn't figure out how to use the grub that buildroot created.  next, I booted qemu using the ISO as boot and the disk image as the hard drive.  I installed grub onto the hdd image (from inside qemu) and tried to boot from the drive.  No luck, I get an error stating that the drive is read only and all the attempts to open /dev/* fail.  I googled the error code and all the answers pointed to a corrupt drive.  I started all over and got the same error.

My Skills:  I have a few years of experience writing c++ code for embedded systems (linux and wince), but the OS builds have always been done by someone else.  I have experience using linux, but very little experience configuring it.

Questions:
1) is this the right approach, or am I missing an obvious step?
2) is there a reason that the inittab file only has getty on a serial port by default?
3) what is the recommended way of making changes to buildroot so that when a new version comes out I don't lose all my changes.  I thought that I would just need to put my .configs into source control, but it looks like I need to change the inittab file in the skeleton.  How do other people handle configuration changes that aren't covered by any of the .configs (or the various make menuconfigs)?

Note:  I didn't search the buildroot archives.  I tried, but I keep getting an error from google stating that I have been blocked from that service.  I found a number of tutorials online on how to get a bootable buildroot image, but they all assumed that I had grub on the development machine and my attempts at tweaking them haven't worked so far.

Jake

[Buildroot] need help making bootable image

[Bjørn Forsman]

On 19 November 2011 21:51, Jacob Sullivan <mail@jakesullivan.com> wrote:
[...]
> Questions:
> 1) is this the right approach, or am I missing an obvious step?

I haven't worked with ISO images + Buildroot, so I don't really have
any comments.

> 2) is there a reason that the inittab file only has getty on a serial port by default?

I think Buildroot is used most often on headless systems.

> 3) what is the recommended way of making changes to buildroot so that when a new version comes out I don't lose all my changes. ?I thought that I would just need to put my .configs into source control, but it looks like I need to change the inittab file in the skeleton. How do other people handle configuration changes that aren't covered by any of the .configs (or the various make menuconfigs)?

I personally use git branches.

For your .config file: make savedefconfig && cp defconfig
configs/myconfig_defconfig

Now Buildroot will list your config file when "make help" and load the
configuration when "make myconfig_defconfig".

Best regards,
Bj?rn Forsman

[Buildroot] need help making bootable image

[Thomas Petazzoni]

Hello,

Le Sat, 19 Nov 2011 12:51:06 -0800,
Jacob Sullivan <mail@jakesullivan.com> a ?crit :

> Current status.  I have a buildroot ISO image that I can boot in qemu
> and a buildroot ext2 image that I can mount either in ubuntu or in
> qemu when I boot with the ISO image.  The changes that I made to the
> default build are minimal.  I added ext2 to buildroot and the kernel,
> added nano to buildroot and fdsk to busybox.  I also changed the tty
> in buildroot to tty1 so that I could get a console prompt when I
> booted in qemu.  I made an empty disk image, mounted it and made a
> primary partition formatted ext2, mounted that and copied in the root
> file structure.  I then unmounted it and tried to install grub on the
> image.  ubuntu has grub 2, and I couldn't figure out how to use the
> grub that buildroot created.  next, I booted qemu using the ISO as
> boot and the disk image as the hard drive.  I installed grub onto the
> hdd image (from inside qemu) and tried to boot from the drive.  No
> luck, I get an error stating that the drive is read only and all the
> attempts to open /dev/* fail.  I googled the error code and all the
> answers pointed to a corrupt drive.  I started all over and got the
> same error.

I don't understand why you're trying to mix an ISO image and an ext2
partition here. Why don't you simply make your ext2 image bootable ?

I have some script stuff that does that here (create partitions,
loopback mount them, install grub, etc.), I could extract it and make it
available if you're interested.

> 1) is this the right approach, or am I missing an obvious step?

The steps to install Grub, create partitions and so on require to be
root, this is the reason why Buildroot does not do this work. But
certainly, we could better document how to proceed to do these things.

> 2) is there a reason that the inittab file only has getty on a serial
> port by default? 

As answered by Bjorn, typical embedded systems use a serial port for
debugging purposes.

> 3) what is the recommended way of making changes to
> buildroot so that when a new version comes out I don't lose all my
> changes.  I thought that I would just need to put my .configs into
> source control, but it looks like I need to change the inittab file
> in the skeleton.  How do other people handle configuration changes
> that aren't covered by any of the .configs (or the various make
> menuconfigs)?

You should not change the inittab of the skeleton, because that will
prevent you from making upgrades to newer Buildroot versions.

Instead, use a custom post-build script (BR2_POST_BUILD_SCRIPT) that
tweaks the inittab.

See http://elinux.org/images/2/2a/Using-buildroot-real-project.pdf,
page 22, 23, 24 and 25.

> 
> Note:  I didn't search the buildroot archives.  I tried, but I keep
> getting an error from google stating that I have been blocked from
> that service.

The archives are available at
http://lists.busybox.net/pipermail/buildroot/. Do you have a problem
access this URL ?

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] need help making bootable image

[Jacob Sullivan]

On Nov 20, 2011, at 12:26 AM, Thomas Petazzoni wrote:

> Hello,
> 
> Le Sat, 19 Nov 2011 12:51:06 -0800,
> Jacob Sullivan <mail@jakesullivan.com> a ?crit :
> 
>> Current status.  I have a buildroot ISO image that I can boot in qemu
>> and a buildroot ext2 image that I can mount either in ubuntu or in
>> qemu when I boot with the ISO image.  The changes that I made to the
>> default build are minimal.  I added ext2 to buildroot and the kernel,
>> added nano to buildroot and fdsk to busybox.  I also changed the tty
>> in buildroot to tty1 so that I could get a console prompt when I
>> booted in qemu.  I made an empty disk image, mounted it and made a
>> primary partition formatted ext2, mounted that and copied in the root
>> file structure.  I then unmounted it and tried to install grub on the
>> image.  ubuntu has grub 2, and I couldn't figure out how to use the
>> grub that buildroot created.  next, I booted qemu using the ISO as
>> boot and the disk image as the hard drive.  I installed grub onto the
>> hdd image (from inside qemu) and tried to boot from the drive.  No
>> luck, I get an error stating that the drive is read only and all the
>> attempts to open /dev/* fail.  I googled the error code and all the
>> answers pointed to a corrupt drive.  I started all over and got the
>> same error.
> 
> I don't understand why you're trying to mix an ISO image and an ext2
> partition here. Why don't you simply make your ext2 image bootable ?
> 
> I have some script stuff that does that here (create partitions,
> loopback mount them, install grub, etc.), I could extract it and make it
> available if you're interested.

I tried to make the ext2 image bootable (that is the only thing I can't seem to make work).  I went down the iso path because that image would boot and had a version of grub that was the same as in the ext2 image.  I would love to have a copy of the scripts.

> 
>> 1) is this the right approach, or am I missing an obvious step?
> 
> The steps to install Grub, create partitions and so on require to be
> root, this is the reason why Buildroot does not do this work. But
> certainly, we could better document how to proceed to do these things.

how should I install grub?  Since my dev machine has grub2, I thought booting from the ISO image would be a good workaround... I also thought that the whole idea of fakeroot was so that tools like buildroot could do these types of tasks...

> 
>> 2) is there a reason that the inittab file only has getty on a serial
>> port by default? 
> 
> As answered by Bjorn, typical embedded systems use a serial port for
> debugging purposes.
> 
>> 3) what is the recommended way of making changes to
>> buildroot so that when a new version comes out I don't lose all my
>> changes.  I thought that I would just need to put my .configs into
>> source control, but it looks like I need to change the inittab file
>> in the skeleton.  How do other people handle configuration changes
>> that aren't covered by any of the .configs (or the various make
>> menuconfigs)?
> 
> You should not change the inittab of the skeleton, because that will
> prevent you from making upgrades to newer Buildroot versions.
> 
> Instead, use a custom post-build script (BR2_POST_BUILD_SCRIPT) that
> tweaks the inittab.

Ah.  That is what I was looking for.  I would love sample post-build scripts if you have any.

> 
> See http://elinux.org/images/2/2a/Using-buildroot-real-project.pdf,
> page 22, 23, 24 and 25.

This was really useful, there should be a link to this from the buildroot doc or faq page.  In all my google searches for other buildroot problems, this didn't come up, but should have.

> 
>> 
>> Note:  I didn't search the buildroot archives.  I tried, but I keep
>> getting an error from google stating that I have been blocked from
>> that service.
> 
> The archives are available at
> http://lists.busybox.net/pipermail/buildroot/. Do you have a problem
> access this URL ?

No, I'll download those and search them.  My problem is from the search bar on this page: http://buildroot.uclibc.org/lists.html
I get this strange error from google... "
We're sorry...

... but your computer or network may be sending automated queries. To protect our users, we can't process your request right now.

See Google Help for more information."

> 
> Best regards,
> 
> Thomas
> -- 
> Thomas Petazzoni, Free Electrons
> Kernel, drivers, real-time and embedded Linux
> development, consulting, training and support.
> http://free-electrons.com

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[Buildroot] need help making bootable image

[Thomas Petazzoni]

Hello,

Le Sun, 20 Nov 2011 14:34:42 -0800,
Jacob Sullivan <mail@jakesullivan.com> a ?crit :

> > I don't understand why you're trying to mix an ISO image and an ext2
> > partition here. Why don't you simply make your ext2 image bootable ?
> > 
> > I have some script stuff that does that here (create partitions,
> > loopback mount them, install grub, etc.), I could extract it and
> > make it available if you're interested.
> 
> I tried to make the ext2 image bootable (that is the only thing I
> can't seem to make work).  I went down the iso path because that
> image would boot and had a version of grub that was the same as in
> the ext2 image.  I would love to have a copy of the scripts.

Basically, you have a version of Grub available in
output/staging/sbin/grub that you can use to install Grub.

I'll try to clean up the script, but it unfortunately won't be this
week as I'm busy with many other things.

> how should I install grub?  Since my dev machine has grub2, I thought
> booting from the ISO image would be a good workaround... I also
> thought that the whole idea of fakeroot was so that tools like
> buildroot could do these types of tasks...

fakeroot can do *some* things, but not everything.

> > Instead, use a custom post-build script (BR2_POST_BUILD_SCRIPT) that
> > tweaks the inittab.
> 
> Ah.  That is what I was looking for.  I would love sample post-build
> scripts if you have any.

There's one little sample script in the slides, do you more examples ?

> This was really useful, there should be a link to this from the
> buildroot doc or faq page.  In all my google searches for other
> buildroot problems, this didn't come up, but should have.

My intention was to make improvements to the Buildroot documentation by
integrating some aspects of those slides.

> No, I'll download those and search them.  My problem is from the
> search bar on this page: http://buildroot.uclibc.org/lists.html I get
> this strange error from google... " We're sorry...
> 
> ... but your computer or network may be sending automated queries. To
> protect our users, we can't process your request right now.
> 
> See Google Help for more information."

Ah, okay, I never used the search engine for the mailing list archives.

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com